Comments and whitespace

From Erights

Line comments

The character ‘#’ begins a line comment, which may occur anywhere; all characters up to the end of the line are ignored. The characters ‘>’ and ‘?’, which denote Updoc, begin line comments if and only if they are the first non-whitespace character at the beginning of the line.

If the preceding line ended with a line continuation character, then a ‘?’ is a syntax error.

Rationale:

This avoids potential ambiguity over whether ‘?’ is a such-that operator or Updoc. Decision.